If you mean a waterblock that covers both the GPU AND RAM then there are a couple that do that like the Innovatec Cool-Matic models but they are limited to 1/4" inlets/outlets which will kill flow in a 1/2" ID based system. If you just want a block to cover just the GPU and then use ramsinks on the RAM then basically any GPU block that fit the Nvidia FX series should fit. Popular ones are the DangerDen Maze4, the SwiftTech MCW50, and the Silverprop SL/HL.